The present embodiments relate to rendering in medical imaging. For three-dimensional visualization, different rendering approaches provide different information to assist the physician in diagnosis or treatment. Two common approaches are the volume rendering technique (VRT) mode and the maximum intensity projection (MIP) mode.
In traditional volume rendering (e.g., VRT by ray cast or other object oriented techniques), each pixel of the final image is sampled along the viewing direction as a direct function of collected samples within the viewing volume. In VRT, each image sample on the viewing direction of one pixel is classified as a color sample then composited to the final image. In MIP, the sample with the maximum value is assigned to one pixel of the final image.
MIP mode is often used for examining vasculatures in contrast enhanced computed tomography images since almost all contrast-enhanced vessels may be viewed in a single image to assess conditions of stenosis, plaque, and stents. MIP renders a great overview of the data, and the noise in the data is naturally filtered out due to lower intensities of noise voxels. However, MIP mode viewing may be misleading in terms of depth perception. Direction and relations between curved vasculature may appear incorrectly placed or connected, especially when multiple vascular branches overlap on the image.
VRT mode provides a view of the objects after image intensities are globally classified into colors. VRT offers better perception of depth and provides good structural understanding as compared to MIP, but suffers from too much occlusion from unimportant voxels and noise and suffers from lack of conspicuity.
Due to the different qualities, VRT and MIP are often both used to make a clinical assessment. However, these two modes are traditionally completely separate entities, each offering different information and tradeoffs but also different configurations of window levels, classification, and other parameters. The user is faced with reconfiguring to switch modes. Even where switching is simpler, the user views both separately or in sequence. The user has to imagine the physical condition of the reviewed structures from the two views.